Field of the Invention
The present invention relates to a charging member, a process cartridge, and electrophotographic apparatus.
Description of the Related Art
At the present time, a contact charging method is one of the method for charging the surface of an electrophotographic photosensitive member. In the contact charging method, a DC voltage or a DC-AC superimposed voltage is applied to a charging member disposed in contact with or adjacent to an electrophotographic photosensitive member, and a micro discharge between the charging member and the electrophotographic photosensitive member is caused to charge the surface of the electrophotographic photosensitive member.
The structure of a charging member for use in a contact charging method typically includes a support and an electro-conductive elastic layer disposed on the support, from the viewpoint of sufficiently securing a nip between a charging member and an electrophotographic photosensitive member. In order to prevent the adhesion of toner and the like to the surface of a charging member, and in order to prevent low molecular weight components contained in the electro-conductive elastic layer from bleeding to the surface of the charging member, a surface layer is typically disposed on the surface of the electro-conductive elastic layer.
Japanese Patent No. 2894508 discloses that a hydroxystyrene resin-containing resin layer disposed on an electro-conductive elastic layer can prevent fusing between a charging layer and an electrophotographic photosensitive member and contamination of a charging member with toner. And Japanese Patent Application Laid-Open No. 2001-173641 discloses a charging roll having an electro-conductive elastic layer with the circumferential surface coated with an organic-inorganic hybrid coating film, which prevents low molecular weight components from bleeding to the surface.
The present invention is directed to providing a charging member capable of inhibiting the effect of the contact mark on the electrophotographic image, even after in contact with another member for a long term.
The present invention is also directed to providing a process cartridge and an electrophotographic apparatus capable of stably forming a high quality electrophotographic image.